U. S. D. A., IJ. K. Bui. 6G, Part I. Issued March If!, 1907. 



SOiME INSECTS INJURIOUS TO TRUCK CROPS. 



THE ASPARAGUS MINER. 



(Agromyza simplex Loew.) 



By F. n. Chittenden, 



Enlnmol agist in Charge of Breeding Experiments, 



The stalks of asparagus are frequently attacked by insects, and in 

 recent years have been reported considerably injured by the larva or 

 maggot of a minute black fly to which the name asparagus miner has 

 been given. The larva mines under the epidermis of the stalk, and 

 when it has transformed to the puparium or "flaxseed" stage the thin 

 outer skin becomes more or less ruptured and the presence of the 

 insect is easily detected. It operates more abundantly near the base 

 of the stalks and penetrates l)elow the surface of the groimd to a 

 depth of 7 or 8 inches. During the year 190f) this species attracted 

 considerable attention by its abundance in some of the principal 

 asparagus-grownng sections of New England and it bids fair to become 

 a pest of considerable importance. It was first noticed on asparagus 



Fig. 1. — Agromyza simplex: Fly, dorsal view at left, lateral view at right. Highly magnified 



(original). 



in 1896, ten 3^ears earlier than the present writing, prior to which 

 time nothing was known of its habits. It is a native species and evi- 

 dently restricted to asparagus as a food plant. Until the year 1900 

 it had not been recognized as doing injur}^ to cutting beds, although 

 attack had been observed in various sections. The mines of the larvae 

 about and below the bases of the stalks are frequently so abundant 

 that the}^ have the eli'ect of girdling, so that the injured stalks can be 

 readily pulled from the ground. 



DESCRIPTIVE. 



The parent insect is a two-winged 11}' (tig. 1), metallic black, with 

 large prominent head and e3'es, and clear wings, the wing expanse 

 being about one-sixth of an inch (4 mm.). 



